Semi-conductor barrier layer system



Aug. 29, 1961 A. A. M. KOETS EI'AL 2998554 SEMI-CONDUCTOR BARRIER LAYER SYSTEM Filed March 25, 1958 2 Sheets-Sheet 1 Fl G.2

NVENTOR AUGUSTINUS ALOYSIUS ANTONIUS MARIA KOETS PIETER WILLEM HAAIJMAN JOHANNES JACOBUS ASUERUS PLOOS VAN AMSTEL AGE 8 1961 A. A. A. M. KOETS ETAL 2,998,554

SEMI-CONDUCTOR BARRIER LAYEIR SYSTEM Filed March 25, 1958 2 Sheets-Sheet 2 FIG.3

300 50C 5O mW INVENTORS AUGUSTINUS ALOYSIUS ANTONIUS MARIA KOETS PIETER WILLEM HAAIJMAN JOHANNES JACOEUS ASUERUS PLOOS \AN AMSTEL Unted States Patent SEMI-CONDUCTOR BARRIER LYER SYSTEM Augustinus Aloysius Antonius Maria Koets, Mollenhutseweg, Nijmegen, and Johannes Jacobus Asuerus Ploos van Amstel and Pieter Willem Haaijman, Eindhoven, Netherlands, assignors to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Mar. 25, 1958, Ser. No. 723,890 Claims priority, application Netherlands Apr. 5, 1957 12 Claims. (Cl. 317-234) This invention relates to semi-conductor barrier layer systems, for example transistors or crystal diodes, provided with vacuurn-tight envelopes which, at least in the surroundings of the semi-conductor systems, contain an active amount of water vapour. This invention also relates to methods for mounting such semi-conductive barrierlayer systems in vacuum-tight envelopes.

As is known, the surface condition of a semioonductor system comprising a bar-rier layer system greatly afiects the electrical properties of the barrier layer system. 'Ihus, in a transistor, the current amplification factor is very sensitive to substances or gases adsorbed at the surface of the semi-conductive member. The term current amplification factor," which hereinafter is also denoted as used herein is to be understood to mean the quan tity which is defined by the equation where Al and A1 represent the variations in the collector and base cnrrents respectively, which are rneasured at a constant potential diterence V between the emitter and collector contacts. The influence of water vapour on the physical properties of a germanium surface has been examined several times and described in the literature. From the Proceedings of the Institute of Radio Engineers, April 1956; volume 44, Number 4, pp. 494-503, it is known that by adsorption of water vapour at the surface of a germanium transistor the current amplification factor is considerably increased, while other properties, for example the.collector breakdown voltage and the collector cutcurrent, provided that the hum-idity is not made excessively large, are either improved also or deteriorated immaterially on1y.

However, experience has shown that, as will be seen from the above-mentioned article also, the stability of the known barrier layer systems, in which water vapour is adsorbed at the surface of the semi-eonductive systern, is unsatisfactory, that is to say, that the electrical properties of these barrier layer systems greatly deteriorate after use for some time and at high operating temperatures. This deterioration of, for example, the current amplification factor is particularly marked when the transistor is heavily loaded temporarily, ior example, by a temperature increase to 85 C. or by a heavy electrieal load. 'I'heret'ore, a completely different stabilization process has been proposed in which the water vapour and any further adsorbed substances are removed from the surface as far as possible by heating the transistor during mounting to a high temperature, for example 140 C. in a vacuum tor sorne hours. However, this process, which is known as "vacuum bakng," has a disadvantage in that the high stability is obtained at the expense of the current amplifieation factor, which in this proces: drop: trom its high value found after final etching to a. very iow value. Furihermore, in this process, there is a. technical cliifieulty in that the barrier layer system must be mounted in condiii0ns which can hardly be maintained, that is to say, in

a vaeuum.

It. is an object of the present invention to provide meesures which can be taken without difliculty and ensure a high degree of stability of a barrier layer system provided with a vacuumtght envelope at the van'ous operating temperatures while retaining the favourable electrical properties, such as a high current amplification factor, a small cut-off or saturation current or a high breakdown voltage, which such a barrier layer syrtern can exhibit in a water vapour environment. It is a particular object of the nvention to provide a transistor having a vacuumtight envelope which combines a high current arnplifica tion factor with a high stability.

The invention utlizes the known efiect that water vapour has a favourable influence on a number of semiconductive barrier layer systems, -for example the systems in which the semi-conductor is germanium. However, the nvention also provides a better understanding of the causes of the instabilty of the known semi-conductive barrer layer systems which are not treated in a vacuum.

The invention is based inter alia on the recognition that this instability is largely due to a decrease with time of the operative water vapour content withn the envelope, more particularly in the environment of the semi-conductive system. The cause of this decrease is assumed to be the presence of component parts within the envelope or of the envelope itself which absorb water vapour or react with water vapour, such as glass or metal parts or a filler, which wthdraw the operative water vapour from the surroundings of the semi-conductive system at a low rato in normal operaton, but at a hgher rato by reaction onder certain conditions, for cxarnple by heating.

According to the invention, in a semi-conductive barrer layer system provided with a vacuum-tight envelope which, at least in the surroundings of the semi-conductive system, contains an operatve amount of water vapour, there is also provided withn the envelope a depot or source of water in the bound state and this depot has a large relative quantty of water with respect to any reactions of water with or adsorption of the water by other parts within the envelope or of the envelope itself. Obviously, the term operative quantity of water vapour" is used herein to denote -an amount of water vapour which may be different with different semi-conductors but is suflicient to exert a favourable infiuence on at least one of the electrical proporties of the barrier layer system. The term water depot or source is used herein to denote a substance to which an amount of water is bound and which, when the operative water vapour content in the said surrounding decreases, is capable of supplying water vapour, but is also capable of absorbing water under certain conditions, for example at a drop in temperature, and consequently of exerting a stabilizing influence upon the operative water vapour content within the envelope. The term large relative quantity of water is to be understood to mean an amount such that for a prolonged period of time, that is to say, throughout the life of the barrier layer system, the water depot contains a suficient amount of water to compensate for the losses.

Preferably, the water depot consists of a substance to which or in which an amount of water is bonnd and which at an increase in temperature yields water vapour to counteract the evaporation of water from the semieonductor surface and, at a subsequent decrease in temperature, absorbs an equal amount of water, or, if water vapour has been withdrawn by adsorption or reaction, adsorbs an amount of water such that, after a complete temperature cycle, the original relative humdity in the surroundings is restored. Further, the water depot is designed so that at the van'ous operating temperatures a favourable relative huimidity is maintained in the said surroundings.

Banier layer systems provided with vacuum-tigh-t en velopes containin-g a water depot in aocordanee with the invention can be operated at a high temperature for a prolonged period of time, for example for 1000 hours, without an appreciable change in the electrical properties.

Obvieusly, the relative humidity of the environment of the semi-conductor system must be kept within the limits in which the water vapeur acts favourably. Not only must an excessive humidity be avoided in order te prevent cenduction along the surface and the like, but also there must be preduoed in the said environment a degree of humidity such that the favourable influence of the water vapeur en the semi-conductor surface is suiiiciently perceptible. Obvieusly, these limits depend inter alia upon the semiconductor used. For a barrier layer system the semi zonductor body of which consists of germanium, an upper limit for the ndmissible water vapeur pressure can be given which is about 15 mms. of Hg at roem temperature and increases with the temperature te a maximum of about 300 mms. at 85 C.; the lower limit at 85' C. is about 10 mms. of Hg for germnnium. However, and this is a further important aspect of the invention, preferably and particularly at the high operating temperatures, u high water vapeur pressure is avoided in order te reduce te a minimum any reactions between the semi-conductor and the water vapeur at a high temperature and a high water vapeur pressure. In a semi-cenductive barrier layer system, the semi-conductive member of which consists of germani urn, use is preferably made of a water depot which at 85 C. maintains a water vapeur pressure of at least 20 mms. of Hg and at the most 100 mms. of Hg.

By a suitable choice of a substance having a faveurable binding afiinity with respect te water, any degree of humidity favourable te the semi-conductor used can be ensured by means of the depot. Substance centaining water of hydration, socalled hydrates, such as zinc ammonium sulphateH o, nickel potassium sulphate 6HO, sodium bromide2H o er ammonium niclrcl sulphate-6H,O and the like, are particularly suited for use as a water depot. They may be mixed with a binder censistng of silicoorganic polymers, a number of which are known under the names of silicone vacu-um grease and silicone oil and are commercially available under the trademarks "Dow Corning DC7" and Dw Cerning 702, alternatively, they mny be mixed with a filler, for example zand. However, if the substance concerned is chemically reactive with respect te the semiconductive system, it is preferably separated therefrom by means of a poreus wall which may consist of glass wool er asbestos.

In general, as water depot use can be made of substances which are capable of reversibly yielding and ab sorbing water and of maintaining a faveurable water vapeur pressure at the various operating temperatures. Suitable substances are a number of oxides together with their hydroxides, for example the system thallium hydroxide-thallium oxide or the system magnesium hydroxide-magnesium oxide, a number of aqueous solutiens, for example en aqueous eolution of calcium chloride er manganese chloride er phospheric acid, and substances such as silica gel or slliee-organic compounds, for example silicone vacuum grease, which have abeorbed a sutlicient amount of water. It is already known to provide silical gel er silicone vaeuum grease in an envelope for a sernlconduetor barrier layer system, but these mbrtancee were provided as dry as possible in order to exelude water trom the eurreundingse! the semi-oonductlve member. However, when these substancee iue employed in e barrier layer system in accordance with the invention, they must have abeorbed e suficient ameunt of water prior to their provision. Thus, the known barrier layer system is distinguished trom the barrier layer eystem in aocordance with the invention in that, when it is heavily loaded, the water vapeur content which, though slight, is inevitably present,

is consumed in a short period of time, se that the electrical proporties of such a system are highly variable.

The invention also relates te a method of mounting a barrier layer system in a vacuum-tight envelepe, a water depot being providcd within the envelope prior te sealing.

In order that the invention may readily be carriecl out, some embodiments thereof will -new be described, by way of example, with reference to the accompanying diagrammatic drawings, in which FIG. 1 is a longitudinal sectienal view of a transistor provided with a vacuumtight glass envelope and a water depot in accordance with the invention,

FIG. 2 is a diagram which shows the variation of the current ampl-ificatien factor of four transistors mounted without the use of the invention, in which the current amplification factor is plotted as the ordinate and the time during which the transistors are subjected to an endurance test in hours as the abscissa, as compared with the current amplificatien factor of a transistor in accordance with the invention.

FIGURES 3 and 4 are similar diagrams relating te various transistors in accordance with the invention.

FIG. 5 is a cross-sectl'onal view of a modification.

The germanium transistor 1 shown in FIG. 1, the manufactu-re of which will be described more fully hereinafter, is meunted in a vacuum-tight glass envelope oom prising twe parts which are sealed te ene another, a glass base 2 and a gl-ass bulb 3. According te the invention, provision is made within the envelope of a water-depot 4 consisting of a mixture of silicone vacuum grease and a hydrate, for example, zinc ammonium sulphatell o. This mixture substantially fills the entire envelope. The electrodes of the transistor are conneeted te supply conductors 5, 6 and 7 which are brought out through the glass base 2.

The results obtained by the use of the invention will n0w be compared with the results obtained with known transistors in which the semi-conductor system proper was manufactured as follows:

A single crystal r0d consisting of n-type germanium of 3 te 5 ohms-cm., is divided in discs of dimensiens 2 x 3 X 0.25 mm. by sawing and grinding. The 2 x 3 mm. surfaces of these discs coincide with the crystallographic (lil) piane. The discs are ground and subsequently etched to a thickness of about 150 micrens in a solutien consisting of an aqueous 48% HF-solution, a 66% aque- 0us solution of HNO and H 0 in a volume ratio 2:2: 1, subsequently washed in dcionized water and dried. Centrally of a 2 x 3 mm. surface of such a germanium disc, there is provided an emitter pellet of diameter approxi mately 400 microns which consists of pure indium and is sccured te the germanium disc by heating for a short period of time. Simultaneously, there is provided eccentrically en the same surface a base terminalconsisting of nickel to the end of which a small ameunt of selder consisting of a tin-antimony alley by weight of Sn, 5% by weight of Sb) is provided. On the opposite surface of the disc, an indium collector pellet of diametet 800 microns is centered with respect te the emitter pellet and likewise secured by short-time heating. Subsequently, the assembly is heated te 600 C. in an atmosphere een sisting of hydrogen and nitrogen for about 10 minutes The basethickness of the alloy transistors thus produced proves te be about 30 microns. Subsequently, a supplj wire is welded te the base contact plate and nickel sup ply wires are soldered to the emitter and collector elec' trodes. In an aqueous 40% NaOH-slution, the tran sister is etched electrolytically for about 10 seconds, the collector heing conneeted te the pesitive terminal and the negative terminal eonsisting of a platinum plate suspended in theetching bath. After being washed in het de-ieuized water and dried, the transistor can be mounted in a vacuurn-tight envelope. In order te check the stability of barrier layer system provided with a vacuum-tight envelope in accerdanc8 with the invention and to compare it with the stability of known systerns produced without the use of the in vention, a nurnber of these semi-conductive systems art sealed together with different kinds of water depots in glass vacuum-tight envelopes, a smaller nurnber being mounted in vacuum-tight envelopes Without the use of the invention. In order to obtain clear indications of any changcs at short notice, part of these mounted transistors were subjccted to a heavy endurance test, which consisted of prolonged heating at 85' C. without the use of an electrical load, another part being subjected to a different heavy endurance test which consisted of prolonged heating at 50 C. and the simultaneous imposition of an elec trical load of 50 milliwatts (collector-base voltage volts; collector current 5 milliamperes). Both endurance tests wcre interrupted for short intervals after periods of 100 hours, 500 hours and 1000 hours, so that the transistors could be cooled to room temperature and at room temperature a number of quantities of the transistors, for example current amplification factor, cut-off or saturation current and noise, could be checked.

FIGURES 2 to 4 show the measurernents of the amplification factor obtained in these tests. The measure ments of the noise and the cut-off current, which both proved to be extremely low and hardly variable, are not shown. For clearly indicating which measuring points relate to a certain transistor, the points associated with a single transistor are joined by straight lines. In all these figures, the beginning of the endurance test is indicated by thetirne O; FIG. 2 also shows a measurement made prior to this instant of the value of the current amplification factor after final etching at the time E.

The transistor to which the characteristic 10 of FIG. 2 relates and which, after final etching, had a current amplification factor of 97, was heated in a vacuum at 145 C. for 3 hours and subsequently sealed in the glass envelope in this completely dry state. Owing to this vacuum baking, the.current amplification factor dropped to 25, that is to say, to about '/4 of its initial value. Subsequently, the transistor was subjected to the endurancetest at 85 C. As will be seen front the characteristic 10, this transistor, which was mounted in a known manner without the use of the invention, had a very good stability; however, the current amplification factor was ;very low.

; Characteristic 11 of FIG. 2 relates to a transistor the current amplification factor of which was about 106 after final etching and which, in a vacuum-tight glass envelope, was surrounded in known manner by silicone vacuum grease, which previously was dried at 100 C. for some time. After the sealing-in process, the current amplification factor was found to have dropped to 89. t urng the subsequent endurance test at 85 C., the curent amplification factor dropped steadily, so that it was ionly 30 after 1000 hours. The stability of this transistor, hich was mounted in known manner without the use of he invention, was particularly bad. After 1000 hours, he glass envelope was broken open and the transistor to ether with the enveloping silicone vacuum grease b'rought into air having a reiative humidity of60% at oom temperature, with the result that the current ampli- I'ication factor gradually. rose again to 96 and thus subtantially reassumed its original value. This behaviour ;ustifies the assumption that the drop of the current amplification' factor during the endurance test was due to a gradual decrease of the water content at the semiconductor surface. The name is proved by the behaviour f the transistors to which the characteristics 12 and 13 f FIG. 2 relate.

The characterstic 12 of. FIG. 2 relates to a transistor e current amplification factor of which was 104 after nal etching. Prior to sealing, the envelope of this tran- 'stor =was filled with air having a relative humidity of 2%. Owing to the sealing process, the current ampli caton factor dropped to 96. Subsequently, the tranuse of the invention.

sistor was subjected to the endurance test at C.; during the first 500 hours, the current amplification factor dropped to 43, and it fell ot slightly only to 37 during the second period of 500 hours. Conscquently, the stability of this transistor, which was mounted without the use of the invention, was had, parlicularly during the first period of 500 hours, while during the second 500 hours' period the current amplification factor was only about one third of the initial value. Aftcr the endurance test, the transistor envelope was broken open and the transistor was brought to room temperature in surroundings consisting of air having a relative humidity of about 60%.

As a result, the current amplification factor rose alrrtost immediately to 98, and this valse is substantially equal to the initial value.

The charactcristic 13 of FIG. 2 t'eiates to a transistor the current amplification factor of which was 76 after final etching and which was sealed in the vacuum-tight envelope after this had been fillcd with air having a relative humidity of about 81%. Subsequent to scaiing-m the current amplification factor was 71 and this high valuc was maintained during the first 500 hours period of the endurance test at 85 C. After 1000 hours, the current amplification factor had dropped to 34. Thus, this transistor, which was mounted without the use of the invention, proved to be unstable in the long run. After the endurance test the envelope was broken open and the transistor was brought at room temperature into air hav ing a rclative humidity of about 60%, with the result that the current amplification factor immediateiy reassumcd its initial value of 76. The higher stability of this transistor during the first 500 hours period as compared with that shown by the characterstic 12 can be ascribed to the higher water vapeur content initially containcd in the envelope of this transistor.

The transistor to which characteristic 14 of FIG. 2 relates was mounted in a vacuumtight envelope with the lt is iliustrated in FIG. 5. Prior to sealing, a water depot 30 consisting of 60 miilgrams of barium chioride2l i o was providcd in the C|0Sd end of the bulb 31. The remaining space in the bulb around the transistor was filled with silicone vacuum grense" 32 and separated from the water depot 30 by means of a porous wail 33 consisting of giass wooi. Prior to the arrangement of the sem-iconductive system 34 in the envelope and the sealing of this envelope, the bulb containing the water depot and the silicone vacuum grease was stored at room temperature in air having a relativc humidity of 60% for some time. 'l'ne current amplification factor, which was 154 after final etching, was found to be 153 after the sealing-in process. Subsequently, this transistor in accordance with the invention was subjected to the endurance test at 85 C. Durng this heavy en durance test, the initial high value of the current application factor was retaincd. The stability of this transistor in accordance with the invention was materially higher than that of the transistors which were mounted without the use of the invention and are shown by the charactcristics 11 to 13 of FIG. 2. In addition, this transistor was capable of withstand-ing the high temperature during the sealing-in process. Obviously, the absolute variations of the current amplification factor are greater in this transistor than in the vacuum-baked transistor according to charactcristic 10, since the absolute value 2150 of the current amplification factor inthis transistor materially exceeds that of the vacuum-baked transistor. l-lowever, the changes produced, which can be largely attributed to measuring errors, are not of practical importance.

Characteristic 15 of FIG. 3 relates to a. transistor in. accordance with the invention, which was mounted in a vacuum-tight envelope which previously was filled for about with a mixture of by weight of silicone vacuum grease and 10% by weight of the hydrate zinc ammonium sulphate-6H;O. The current amplification factor, which was 59 after final etching, fell off slight-iy to 50 owing to the sealing-in process. In the endurance test at 85' C., this value did not change at all.

'Ihe transistor according to the invention to which charactcristic 16 of FIG. 3 relates, was mounted in a vacuum-tight manner in an envelope which prior to scaling had been fillcd with a mixture of 90% by weight of "silicone vacuum grease and by weight of potassium cobalt sulphatv6H0 The current amplification factor, which after the final etching process was 138, was 112 after the sealing-in process. In the endurance test at 85' C., this high valuc was substantially retaincd.

Charactcristic 17 of FIG. 3 shows the result of the cnduraneo test at 85 C. as tncasured with respect to a transistor in aecordance with the invention, the envelope of which was fillcd with sand to which 10 milligrams of the hydrate potassium nickel sulphate-6HO was admixed. The current amplification factor, which after the final ctching and 'sealing-in processes was 172 and 158 respectively, during the first 100 hours period of the cndurance test dropped to about 150, however, this high value proved to be very stable in the course of the endurance test.

The behaviour of a transistor in acconiance with the invcntion the envelope of which was substantially entirely filled up with silica gel which had absorbed 2% by weight of water, is shown in FIG. 3 by characteristic 18. Owing to the high temperature to which the transistor was exposed during the sealing-in process, the current amplification factor dropped from 274 to 78 but during the first 100 hours of the endurance test, the etects of the high sealing-in temperature were apparently obviated by a supply of water from the depot so that the current amplification factor attained a value of about 140 which steadily increased to about 150 during the remainder of the test. This example shows that substances which have adsorbed a sufficient amount of water are also suitable as water depots. For a stable final valne to be attained as soon as possible, such a transistor may, if required,

be subiected, subsequently to the sealingin process, to a stabilizing temperature treatment, for example, heating to 140 C. for 6 hours. Characteristic 19 of FIG. 4 relates to a transistor in accordance with the invention, which was mounted in a glass vacuum-tight envelope which pre viously had been filled with a mixture of 90% by werght of "silicone vacuum grease and 10% by weight of the hydrate zinc ammonium sulphatv6H0. 'I'he current amplification factor, which after the final etching process was 84, atter the scaling-in process was 81. During the endurance test at 50' C. with a simultaneous electrical 10ad of 50 milliwatts the current amplification factor of this transistor mounted in accordance with the nvention remained substantially constant.

The transistor in accordance with the invention to which the characteristic 20 of FIG. 4 relates, was also sub1ected to the same endurance test. This transistor was mounted 111 a glass vacuum-tight envelope containing a water depot which consisted of 35 milligrams of and was separat ed from the sem-conductive system. The space surroundmg the semi-conductive system was filled with silicone vacuum grease and separated from the water depot by means of a porous wall of glasswool. 'I'he current amplification factor, which was 90 after the final etching process, was 88 after the sealing process, and this value proved to be particularly constant in the course of the endurance test.

A high stability durng the endurance test at 50' C. and an electrical load of 50 miiliwatts was also exhibited by the transistor in accordance with the nvention to which characteristic 21 of FIG. 4 relates. In the envelope of this transistor, provision was made of a water depot consisting of 60 milligrams of bariurn chlorideH0 which was separated by a porous wa1l of glass wool trom the semi-conductive system enclosed in "silicone vacuum grease.

The transistor to which characteristic 22 of FIG. 4 relates was mounted in accordance with the invention in a glass vacunm-tght envelope which was filled up with humid silicone vacuum grease" which previously had been stored in a moist atmosphere having a relatve humidity of 60% for 24 hours and had adsorbed about 1.6 millgrams of water per gram of silicone vacunm grease." The current amplification factor, which was about 300 after the final etching process, dropped comparatively slightly, taking into consideration the high initial value, to 230 owing to the sealng-in process, and this very high value remained substantially constant during the endurance test at 50 C. with an electrical load of 50 milliwatts. This example shows that silicone vacnum grease," which has adsorbed a sufficient amount of water, is also suitable as the water depot.

Finally, it should be noted that the inventon obviously is not restricted to the embodiments of water depots or envelope structures described hereinbefore, nor to semiconductive electrode systems mounted in the special way of the examples. Furthermore, its field of application is not restricted to semiconductive barrier layer systems the semi-conductive member of which consists of germanium; it can be used with the same good results in mounting semi-conductive barrier layer systems in which use is made of any semi-conductor, one or more physical properties of which are favourably influenced by water vapour.

What is claimed is:

1. A semiconductor device comprising a vacuum-tight envelope containing an atmospherc n.Cit1ding water vapor, a semiconductive body and contacts thereto withn said envelope and exposed to the atmosphere therewihin. said semiconductive body beng constituted of a matcrial at which improved properties are exhibted by the body and contacts in a water vapor atmosphere, and a source of bound water vapor withn said envelope and containing sufficient water and capable of gencrating and absorbing water to maintain the water vapor atmosphcrc thercwithin at which the improved properties are exhibited for a lifetirne of nse of such device.

2. A device as set forth in claim 1 wherein a porous wall member within the envelope separates the water vapor source from the semiconductive body and its contacts.

3. A transistor semiconductor device comprising a vacuum-tight envelope containing a water vapor atmosphere, a semiconductive body and contacts I'1CI'CIQ forming a transistor withn said envelope and the body having its surface exposed to the water vapor almospherc, said semicondnctive body being constituted of a matcrial at which improved current amplificatin is exhibited by the transistor in a water vapor atmosphcre, and a source of bound water vapor withn said envelope and containing sufiicient water and capable of reversibly gencrating and absorbing water to maintain the water vapor atmosphcre within the envelope at which the improved properties are exhibited for a lifetime of use of such device.

4. A device as set forth in claim 3 wherein the source comprises a hydrate.

5. A device as set forth in claim 3 wherein said source contans an oxide-hydroxide mixture.

6. A device as set forth in claim 3 wherein said source comprises a mixture of an oxide and the reaction product of the said oxide and water.

7. A transistor device comprising a vacuum-tight en velope containing a water vapor atmosphere, a semiconductve body and contacts thereto forming a transistor withn said envelope with the body surface exposed to the water vapor atmosphere withn said envelope, said semiconductive body being constituted of germaniun whereby the transistor exhibits improved current ampl'r fication when the body is exposed to a water vapor atmo phere, and a source of bound water vapor withn s envelope and containing suflicent water and capable reversibly generating and absorbing water to maintain t 9 water vapor atmosphere within the envelope at which the improved cnrrent amplification is exhibited for a lifetime of use of such device.

8. A device as set forth in claim 7 wherein said water vapor atmosphere is maintained at 85 C. at a pressure between 10 and 300 mms. of mercury.

9. A device as set forth in claim 8 wheren the source comprises a silicoorganic polymer containing absorbed water.

10. A device as set forth in claim 7 wherein the source comprises a substantially inert fi11 admixed with a watercontaining substance.

11. A transistor semiconductor device comprising a vacuum-tight envelope containing a water vapor atmosphere at a pressure between 20 and 100 mms. of mercury at 85 C., a semiconductive body and contacts thereto forming a transistor within said envelope and exposed to the atmosphere within said envelope, said semiconductive body being constituted of gerrnaniurn at which mproved current amp1ification is exhibited by the transistor in a water vapor atmosphere, and a 111 containing bound water Within said envelope and adapted to mantain the water vapor atmosphere therewithin in the said pressnre range whereby the mproved amplificaton is exhibited.

12. A device as set forth in claim 11 wherein the fi11 comprises silicone vacuurn grease containing absorhed 10 water.

References Cited in the file of this patent UNITED STATES PATENTS 15 2,846,625 Gustafson et al. Aug. 5, 1958 2858,356 Setchell Oct. 28, 1958 2,887629 Nijland et al. May 19, 1959 

1. A SEMICONDUCTOR DEVICE COMPRISING A VACUUM-TIGHT ENVELOPE CONTAINING AN ATMOSPHERE INCLUDING WATER VAPOR, A SEMI-CONDUCTIVE BODY AND CONTACTS THERETO WITHIN SAID ENVELOPE AND EXPOSED TO THE ATMOSPHERE THEREWITHIN, SAID SEMICONDUCTIVE BODY BEING CONSTITUTED OF A MATERIAL AT WHICH IMPROVED PROPERTIES ARE EXHIBITED BY THE BODY AND CONTACTS IN A WATER VAPOR ATMOSPHERE, AND A SOURCE OF BOUND WATER VAPOR WITHIN SAID ENVELOPE AND CONTAINING SUFFICIENT WATER AND CAPABLE OF GENERATING AND ABSORBING WATER TO MAINTAIN THE WATER VAPOR ATMOSPHERE THEREWITH- 